GWP ROI Calculator
Is a free gift actually cheaper than a discount? Run your numbers and find out.
Every gift-with-purchase promo is a bet: give away a product so shoppers spend more. This calculator prices that bet with your store's own numbers, then puts it head-to-head against the alternative most merchants reach for first: a discount. The math usually isn't close, because a gift costs you wholesale while the shopper values it at retail. A discount costs you face value, every time.
The same incentive as a discount
To hand shoppers the same — of perceived value with a discount code, you give up — per month in margin. The gift delivers it for —. Running a gift instead of a discount keeps — per month in your pocket.
Like those numbers? Make them real.
Promo Party Pro runs threshold gifts, gift picker popups, and scheduled campaigns on Shopify. $19 per month flat, 15-day free trial.
How the Math Works
The model is deliberately simple, and every assumption is visible:
- Stretched orders. Orders below your threshold, times your stretch rate. These are the shoppers who add one more item because the progress bar says they're close to a free gift.
- Incremental revenue. Each stretched order is assumed to grow from your AOV to the threshold. If your AOV is $195 and the threshold is $250, a stretched order adds $55. Carts that start further below the threshold stretch less often but add more when they do; the AOV-to-threshold gap is the middle of that range.
- Gift cost. Everyone who qualifies gets the gift: the stretchers plus the orders that were landing above your threshold anyway. Gifts are costed at your cost, not retail.
- Net gain. Incremental revenue times your gross margin, minus gift costs, minus $19 for the app.
The discount comparison prices the counterfactual: delivering the gift's retail value as a code ("$15 off when you spend $75") costs you the full face value on every qualifying order. The gift costs you wholesale. That spread, times your monthly redemptions, is the structural advantage of gift-with-purchase, and it's why GWP campaigns protect margin in a way discounts can't.
These results are directional planning numbers, not a forecast. The honest next step is a two-week campaign measured against a no-campaign baseline; here's how to measure it without guessing.
For what that spread looks like at scale, The State of Gift With Purchase 2026 sorts 1,138,230 real Shopify orders by what the customer actually got: gift orders netted $172.88 against $115.65 for price-discounted orders.
Frequently Asked Questions
Why is a free gift cheaper than a discount?
A gift costs you its wholesale cost but the shopper values it at retail. A $34-retail gift that costs you $9 delivers $34 of perceived value for $9 of real cost. A $34 discount delivers $34 of perceived value for $34 of real cost. Same incentive, about a quarter of the price.
What stretch rate should I assume?
The stretch rate is the share of below-threshold orders that add items to reach your gift threshold. With a visible cart progress bar and a threshold set 20 to 30 percent above AOV (how to pick a threshold), 10 to 20 percent is a reasonable planning range. Start conservative and replace the estimate with your own campaign data after two weeks.
Is this calculator's result guaranteed?
No. It is a directional planning model built on your inputs and stated assumptions, not a forecast. Real results depend on your catalog, traffic, gift appeal, and how visibly the promo is merchandised.
Want the offer-design side of this? Get the full FGWP Playbook: which gifts, thresholds, and tiers actually moved revenue in a same-month head-to-head test.